Method for producing a screw foundation

ABSTRACT

A method for producing a screw foundation ( 1 ) for anchoring building parts or structures in the ground, comprising the following steps: providing a tubular starting material ( 10 ) with a required length, laying a free end ( 12 ) of the tubular starting material ( 10 ) between at least two shaped elements ( 20 ), securing the tubular starting material ( 10 ) in its longitudinal direction, compressing the free end ( 12 ) of the tubular starting material ( 10 ) by moving together the at least two shaped elements ( 20 ), with the result that an at least partially tapering region ( 14 ) is formed on the free end ( 12 ) of the tubular starting material ( 10 ), and forming a screw-like or helical thread ( 16 ) on the at least partially tapering region ( 14 ).

TECHNICAL FIELD

The invention relates to a method for producing a screw foundation for anchoring building parts or structures in the ground.

PRIOR ART

Screw foundations are widely used in structural engineering for directly anchoring signposts, masts, canopies and the like in the ground. For this purpose screw foundations, which are also called ground anchors, have a coil-like coarse thread that can be screwed directly into the ground.

In order to produce the screw foundations it is known, for example from DE 198 36 370 A1, to hammer a cylindrical tube into the desired shape. This is generally achieved by using a conical mould into which the cylindrical tube is hammered in the longitudinal direction of the tube. A spike is then welded onto the tapered end of the tube produced in this way. Furthermore, a further tube section is welded onto the opposite end of the tube in order to achieve the desired length of the screw foundation.

Although such screw foundations have proved to be of value in practice, it has been shown that they are associated with a comparably high degree of complexity in production and have weaknesses as regards durability and strength.

DESCRIPTION OF THE INVENTION

It is therefore the object of the present invention to provide a method for producing a screw foundation which enables a simple production process while minimising weaknesses.

This object is achieved according to the invention by a method for producing a screw foundation according to claim 1. Particularly advantageous further developments of the invention are specified in the dependent claims.

The idea forming the basis of the invention is, with a method for producing a screw foundation, to reduce the number of procedural steps directly affecting the later screw foundation such that not only is a simplified procedural sequence produced, but at the same time also a reduced number of interfaces and so of weak points. Against this background the method according to the invention comprises the following steps:

-   -   providing a tubular starting material with a required length,     -   laying a free end of the tubular starting material between at         least two shaped elements,     -   securing the tubular starting material in its longitudinal         direction,     -   compressing the free end of the tubular starting material by         moving together the at least two shaped elements, with the         result that an at least partially tapering region is formed on         the free end of the tubular starting material, and     -   forming a screw-like or helical thread on the at least partially         tapering region.

By means of the use according to the invention of a plurality of moveable shaped elements which compress the free end of the tubular starting material, one can dispense with a number of procedural steps and interfaces which exist in the prior art. Therefore, with the method according to the invention long screw foundations made from a single tubular starting material can also be produced without additional tube sections having to be welded on. In this way a substantial, static and corrosion-related weakness is eliminated.

Moreover, the method according to the invention makes it possible to use a comparably small amount of material and for the screw foundation to have an even wall thickness. Starting materials with different diameters can thus also be processed without changing the shaped elements (this then only requires a longer path of movement for the shaped elements).

Furthermore, it is possible with the method according to the invention to produce a spike required for penetrating and driving into the ground in one piece from the tubular starting material so that corresponding complexity and weaknesses are also avoided here.

According to a further development of the method according to the invention provision is made such that when moved together the shaped elements are acted upon evenly by a hydraulic press. The use of a hydraulic press makes possible an efficient and precise procedural sequence, the even distribution of the pressing force contributing to low internal stresses and so to a high loading capacity of the screw foundation produced.

The number of shaped elements used for compressing is not particularly restricted within the framework of the invention. According to one further development of the invention provision is made, however, such that at least three, preferably at least four shaped elements are used to compress the free end of the tubular starting material. This in turn produces even deformation with low internal stresses.

According to a further development of the method according to the invention provision is further made such that the shaped elements are configured and moved together such that the free end of the tubular starting material is moulded to form a blunt end. In this way material accumulations and concentrations of stress in the region of the free end can be avoided. The inventors have established that a blunt end can also be screwed into most grounds without any problem.

With this concept it is particularly preferred if the free end of the tubular starting material is moulded by the shaped elements such that it has an axial through hole. In this way not only is the screwing in made easier, but the through hole also enables (rain) water, which could otherwise lead to corrosion or frost damage, to flow away.

According to a further development of the invention provision is made, moreover, such that at least one shaped element has at least one projection on its surface facing towards the tubular starting material. In this way the tubular starting material can be secured easily and securely in its longitudinal direction during the pressing process. This applies independently of the length of the tubular starting material, whereas changes to the length with other securing means respectively necessitate alterations. Any indentations in the tubular starting material produced by the at least one projection are of no significance to the present application.

According to a further development of the invention provision is further made such that on the tubular starting material a connection section is additionally formed which is provided on the side of the tubular starting material lying opposite the at least partially tapering region. In this way objects to be anchored can be connected easily and securely to the screw foundation, where it is advantageously also possible to form the connection section using shaped elements that can be moved together.

Within the framework of the present invention the tubular starting material can have different geometries, such as for example a rectangular or round cross-section, and can be produced from different materials. It is particularly advantageous to use stainless steel which combines good deformability with high resistance to corrosion.

A further method according to the invention for producing a screw foundation is the subject matter of independent claim 9. This method ties in with the same inventive idea as the method described above in which the proportion of the procedural steps directly affecting the later screw foundation is to be reduced. For this purpose the method defined in claim 9 comprises the following steps:

-   -   providing a tubular starting material in one piece;     -   dividing the starting material into at least two base elements         respectively along a spiked line, by means of which base         elements respectively having at least two toothed sections are         formed;     -   deforming the toothed sections such that the latter form a         tapering section of the base element;     -   connecting the toothed sections to one another along at least         one welded seam.

With this method one can dispense with strong deformations or compression of the starting material. Therefore the method can be implemented with simple means, and only a very small quantity of starting material is required. Furthermore, the later screwing foundation obtains a very even wall thickness, and the screw foundation can be produced without welding on additional pieces of tube, even in large quantities. This applies in particular if according to a further development of the invention the at least one welded seam is provided in a tapering section.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows diagrammatically a side view of a screw foundation produced by means of a method according to the invention;

FIG. 2 shows diagrammatically a side view of a screw foundation produced by means of a method according to the invention;

FIG. 3 shows diagrammatically a side sectional view of a screw foundation in the course of the method according to the invention;

FIG. 4 shows diagrammatically shaped elements used in the course of the method according to the invention;

FIG. 5 shows diagrammatically an alternative embodiment of the method according to the invention and of a screw foundation produced by the latter.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

In the following preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.

The method according to the invention serves to produce screw foundations 1, as illustrated respectively in a side view, for example in FIG. 1 and FIG. 2.

The screw foundations 1 serve to anchor building parts or structures in the ground, and for this purpose can be screwed into the ground by means of a screw-like or helical thread 16. The thread 16 is provided at least on a tapering region 14 of a starting material or base element 10. Furthermore, the screw foundation 1 has on the end lying opposite the tapering region 14 a connection section 30 which in the present embodiment is formed by a circumferential flange which can include, for example, through holes (not shown) or welded on threaded nuts (not shown).

In the following the method according to the invention for producing the screw foundation 1 will be described with reference to FIGS. 3 and 4. First of all a tubular starting material 10, which can be made for example of stainless steel, is provided with a required length, the tubular starting material 10 possibly having, for example, a rectangular or a round cross-section (hollow cross-section). Then the free end 12 of the tubular starting material 10 is inserted between a number of shaped elements 20, the arrangement of the shaped elements in the present embodiment being shown diagrammatically in FIG. 4.

As can be seen in FIG. 4, the shaped elements 20 can be moved radially between an open position (FIG. 4 a)) and a closed position (FIG. 4 b)). Correspondingly, the shaped elements are moved into the position shown in FIG. 4 a) before inserting the free end 12 of the tubular starting material 10. As soon as the free end 12 is inserted, and for example is positioned by means of a stop, the shaped elements 20 are moved together radially. They are thus acted upon evenly by a press 22 shown diagrammatically in FIG. 3 so that the free end 12 of the tubular starting material 10 is compressed evenly.

Here the projections 24 which are respectively formed on a surface of the shaped elements 20 facing towards the tubular starting material engage in the surface of the tubular starting material 10 so that the tubular staring material 10 is secured in its longitudinal direction.

This compressing of the free end 12 of the tubular starting material 10 is continued until the free end 12 has obtained the desired tapering form, as shown diagrammatically in a sectional view, for example in FIG. 3. The free end 12 shown in FIG. 3 thus has a blunt end 18 which defines an axial through hole 12 a.

Then the pressing force of the hydraulic press 22 is released, and the shaped elements 20 are moved back somewhat so that the starting material 10 can be removed.

Now the screw-like or helical thread 16 is formed on the tapering region 14, for example by welding on corresponding thread coils. Furthermore, the connection section 30 already described above is formed on the tubular starting material 10, for example also by welding on. The production process is thus concluded.

An alternative method according to the present invention for producing a screw foundation 1 will be described in the following with reference to FIG. 5. With this method a tubular, one-piece starting material 10 as already described above is also provided. As shown in FIG. 5 a), this starting material 10 is divided into two base elements along a spiked line 42, by means of which base elements 40 each having two toothed sections 44 are formed.

These toothed sections 44 are now deformed such that the latter form a tapering section 14 of the base element (see FIG. 5 b)). Now the toothed sections 44 are connected to one another along a welded seam 46 which is provided in the tapering section 14.

Finally, although not shown in FIG. 5, a thread in the region of the tapering section 14 and a flange section or the like are provided so that the production of the screw foundation 1 is concluded. 

1. A method for producing a screw foundation (1) for anchoring building parts or structures in the ground, comprising the following steps: providing a tubular starting material (10) with a required length, laying a free end (12) of the tubular starting material (10) between at least two shaped elements (20), securing the tubular starting material (10) in its longitudinal direction, compressing the free end (12) of the tubular starting material (10) by moving together at least two shaped elements (20), with the result that an at least partially tapering region (14) is formed on the free end (12) of the tubular starting material (10), and forming a screw-like or helical thread (16) on the at least partially tapering region (14).
 2. The method according to claim 1, characterised in that when moved together the shaped elements (20) are acted upon evenly by a hydraulic press (22).
 3. The method according to claim 1 or 2, characterised in that at least three, preferably at least four shaped elements (20) are used to compress the free end (12) of the tubular starting material (10).
 4. The method according to any of the preceding claims, characterised in that the shaped elements (20) are configured and moved together such that the free end (12) of the tubular starting material (10) is moulded to form a blunt end (18).
 5. The method according to claim 4, characterised in that the free end (12) of the tubular starting material is moulded by the shaped elements (20) such that it has an axial through hole (12 a).
 6. The method according to any of the preceding claims, characterised in that at least one shaped element (20) has at least one projection (24) on its surface facing towards the tubular starting material.
 7. The method according to any of the preceding claims, characterised in that the tubular starting material (10) has a rectangular or round cross-section.
 8. The method according to any of the preceding claims, characterised in that there is additionally formed on the tubular starting material (10) a connection section (30) which is provided on the side of the tubular starting material (10) lying opposite the at least partially tapering region (14).
 9. The method according to claim 8, characterised in that the connection section (30) is formed with a flange (30) extending around the tubular starting material and which has through holes and/or welded on threaded nuts.
 10. The method according to any of the preceding claims, characterised in that the tubular starting material (10) is made at least partially of stainless steel.
 11. The method for producing a screw foundation (10) for anchoring building parts or structures in the ground, comprising the steps: providing a tubular starting material (10) in one piece; dividing the starting material (10) into at least two base elements (40) respectively along a spiked line (42), by means of which base elements (40) respectively having at least two toothed sections (44) are formed; deforming the toothed sections (44) such that the latter form a tapering section (14) of the base element (40); connecting the toothed sections (44) to one another along at least one welded seam (46).
 12. The method according to claim 10, characterised in that at least one welded seam (46) is provided in the tapering section (14). 